1. Field of the Invention
The present invention relates to a connector for slidably holding an instrument which is used by being inserted into a tube-shaped body in fluid-tight seal condition with the inside of the tube-shaped body, and in particular relates to a connector which is to be connected to a base end portion of a tube-shaped body such as a guide catheter to be inserted into a body, for slidably holding an instrument such as a balloon catheter or a guide wire to be inserted into the tube-shaped body in fluid-tight seal condition with the inside of the tube-shaped body.
2. Description of the Background Art
Up to now, when carrying out medical treatments on stenosis portion of blood vessels caused by arteriosclerosis or the like, Percutaneous Transluminal Coronary Angioplasty (PTCA) is adopted as the typical method of angioplasty. The PTCA is comprised of the steps of inserting a catheter equipped with a dilator such as a balloon at its tip into the stenosis portion of the blood vessel and inflating the dilator so as to dilate the stenosis portion of the blood vessel, thereby improving blood flow at the distal side thereof. During such surgical procedure, before the catheter equipped with the dilator is inserted into the blood vessel, a guide catheter which is used for guiding the dilator-equipped catheter toward the position of the stenosis portion is inserted and then held in place within the blood vessel. At such time, a Y-shaped connector is usually used, which is connected to the base end of the guide catheter before insertion of the dilator-equipped catheter.
As disclosed, for example, in Japanese Utility Model Publications No. 53-44870 and 4-8918, the known Y-shaped connector is composed of a connector body having an insertion passage extending in an axial direction thereof, a seal member formed of an elastic cylindrical body (O-ring) and a control body which is fitted or screwed to the connector body and which is used to change the inner diameter of the seal member by changing the shape of the seal member from the outside of the connector body. Thus, by screwing the control body into the connector body, the resulting pressure causes the seal member to change its shape, and this enables to hold the dilator-equipped catheter passing through the seal member under fluid-tight condition with the inside of the guide catheter.
However, the seal members of these kinds of prior art connectors have a simple cylindrical shape with a predetermined fixed inner diameter that is larger than the outer diameter of the dilator-equipped catheter. Therefore, if the dilator-equipped catheter is slid within the seal member without a complete pressure being applied to the seal member, blood that has flowed due to blood pressure into the inside of the connector will leak out through the spacing between the seal member and the dilator-equipped catheter. On the other hand, if the control body is used to constrict the seal member and thereby reduce the inner diameter thereof in order to prevent such leakage of blood, a major portion of the inner surface of the seal member is forced into pressurized contact with the catheter passing therethrough, resulting in an increase in the sliding resistance for the dilator-equipped catheter, which then makes it difficult to carry out operations with the dilator-equipped catheter. Furthermore, if the constricting force applied onto the dilator-equipped catheter due to the constriction of the seal member is too high, or if the surface contact area between the seal member and the dilator-equipped catheter is too large, there are cases that the dilator-equipped catheter would be damaged and therefore the connector can not be used.
Accordingly, there has been much difficulty in trying to make adjustments to the prior art connectors having a cylindrical seal member with a fixed inner diameter in order to achieve satisfactory results with regards to both fluid-tight seals and slidability of an instrument such as a catheter passing through the seal member.